This is nonsensical extrapolation probably hundreds of years into an ideal future. We aren't there yet and we won't be there for a long time at the current rate of things. Diverting an asteroid of any significant mass is functionally impossible even given years notice today.
Huh? Radiation pressure alone is enough to divert an asteroid if you spot it in time. You don't need nukes, just a rocket and enough paint to change the albedo on one side.
